Packing fluid seals



Patented Jan. 14, 1936 I I UNITED STATES PATENT OFFICES rsoxmo sum) SEALS Wilbur Arthur Laser, Wilmington, DeL, assignor to E. 1. du Pont de Nemours & Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application June 19, 1931; serial'No. 545,487

10 Claims (Cl. 91--68) This invention relates to the manufacture and immune to the attack or the solvent. Preferred use of new compositions of matter suitable for softeners are salts of the higher fatty acids, 1. e., serving as packing for fluid seals. More particu-' soaps, such salts being insoluble in organic sollarly it relates to the art of sealing moving parts vents. Common soap in a dry condition has been of pumps or valves wherein the packing matefound to be a suitable softener for hydrogenated 5 rials are required to resist the solvent action of Castor oil. In addition to the ingredients organic chemicals such as acids, ketones, hydroready named I may use solid lubricants such as carbons, esters and alcohols under high pressure, graphiteand to retain these liquids without leakage. h following examples Show how y fi The packing problem is indeed a very old one, tion may be Carried Out in Practice? 10 and the most diverse compositions of matter have v E 2 1 been described for serving the purpose. In genmmp 9 cm], the more common packing materials of the prior art are composed of fibrous substances impregnated with various lubricants. Such compositions y consist of leather fibers of Vege ture there was added a section of asbestos yarn table origin such as flax or hemp impregnated Weighing about 10 grams. The melted oil wa wlth a 0 i In add o graphite is heated to 200 0., and triturated with the asbestos fl y a d d to hese fibrous greass-impregyarn for about l5minutes after which the yarn 2o hated packing materials to give them better lubriwas removed, d i d, d allowed to cool. The eating p p e ner l fibers are also used, impregnated asbestos obtained under these conas in pack-mg consisting asbestos yam ditions contained about 52% of the hydrogenated pregnatecl with parafin or tallow. Another type f t of packing which has found extensive use con- Example 2 v. d sists of soft shredded metals impregnated with as nd graphite or both. Two hundred twenty grams of hardened castor This invention has as an bject certain oil having a melting point of 75 C. was melted provements in compositions of matter suitable and heated to All this temperature, there for use as pagking was added 25 grams of dry sodium stearate and Fifty grams of completely hydrogenated castor oil having a melting point of Sill-85 C. was melted,

tad

M The objects of my invention are accomplished grams of flake -P fifty grams 30 by impregnating fibr yus materials of egetable shredded asbestos was triturated in the melted animal or mineral origin with m melting fat mixture at 200 C. for 10 minutes, removed, natural or synthetic waxes or wax-like bodies drained d v d to @001. after ch t w which'are resistant to the solvent action of esters. teased out i fine Shreds- For example, I have made extensive tests of the Example 3 35 solubilizing action of ethyl butyrate and other organic solvents on such waxes as beeswax, Oneieighth inch asbestos Y Was p nated spermaceti, and hydrogenated castor oil. Of the y P it through melted mass of y above named materials the t remarkably genated castor oil having a melting point of 70 C.

0 resistant to the action of the solvents and con- Example 4 stitues an example of the material suitable for incorporation into the new compositions of mat- Leather Washers O 'a s table size to fit into ter described in this invention. It has been the Stllfling bo f a high Pressure Solvent D p found th t hydrogenated castor oil, in which the were heated for five minutes at 110 C. in melted and 7.5 grams of graphite added. To this mite M unsaturation ordinarily present in castor oil has hydrogenated Castor Oil having melting t of been satisfied either partially or completely 84? C. Two or more of the treated washers were through the addition of hydrogen, with the proplaned mind T the pump and duction of a. body having the physical characterggfi g i g gi' g into the 7 so istics of a wax, possesses a remarkable resistance Z i gga u um 'proo seal had to the action of such solvents as are commonly encountered. 7 Example 5 In order to overcome the brittleness of some of Shredded lead was impregnated with one-tenth these waxes or wax-like materials, I may add of its weight othydrogenated castor oil having a softeners thereto, said softeners likewise being melting point of 75 C. and 1% of graphite.

Example 6 A mixture of asbestos and linen fibers were felted together in the presence of melted hydrogenated castor oil and rolled into sheets of suitable thickness for the cutting out of gaskets. This gasket material provides an effective seal when placed between sections of alcohol distillation columns and like equipment exposed to the solvent action of organic compounds.

Example 7 In carrying out the catalytic hydrogenation of ethyl butyrate a chemical proportioning pump having a 0.25" piston was employed to force the ester against 3000 lbs. of hydrogen pressure at the rate of 200 cc. per hour. Considerable difiiculty was experienced in satisfactorily packing the pump under these conditions, and all available standard packing materials were tried. Leather impregnated with neats-foot oil, asbestos impregnated with paraflin, and a packing consisting of asbestos, stearin, and graphite were some of the materials that developed serious leaks within a few hours of operation.

As illustrating the advantages accruing from using the compositions of the present invention, under the same conditions of operation when the pump was packed with a composition comprising asbestos impregnated with hydrogenated castor oil and graphite prepared as described in Example 1, no leakage of the ester through the stufilng box was experienced until after a weeks continuous operation.

Example 8 In another process liquid methyl alcohol was pumped against a pressure of only 200 lbs. per square inch, but leakage developed in half an hour when the pump was packed with a standard prior art packing containing grease, graphite, and asbestos.

On the other hand, when asbestos impregnated with hydrogenated castor oil was employed as the pump packing and the process operated under the same conditions as before, no leakage had developed after 200 hours of operation.

In the above examples I have indicated one material which may serve as the waxy component of my new compositions, namely, castor oil which has been hydrogenated. The invention is not limited to this however, for any other wax or waxy material in the form of a single compound or a mixture having similar properties may be used instead. Such other waxy compound or mixture used however will be a high melting derivative of a fatty acid, the melting point being preferably 70 C. or higher, since I have found that such materials in general possess the desired resistance to the action of organic solvents. The fibrous component may be of vegetable, animal or mineral origin. For example, leather, silk or wool, or cotton, hemp, flax or jute fibers or fabrics may be used. Asbestos is, however, to be preferred but it may be used in conjunction with any of the aforementioned fibers. In certain cases it may even be desirable to use a metallic fiber base, either alone or together with one or more of the fibers already mentioned. Graphite may or may not be included in the composition depending on the exact use to which it is to be put. The exact method of impregnating the fibrous material with the waxy component may be varied within wide limits. The fiber base may be woven or braided into strands and later impregnated by dipp g into the melted wax and graphite. Alternatively the elementary fibers may be incorporated into strands or fibers in the presence of or after mixing with the other components. The final compositions may be used in the form of rope, string or strands, or in molded forms such as rings, discs, or sheets.

The new compositions of matter described above are intended primarily for use in packing pumps and valves. They may also be used in other types of stufiing boxes such as are employed in gauge glasses, hydraulic lifts, and presses. The new packing. materials are also well suited to use as gasket material. While they are admirably suited for use in the presence of organic liquids such as acids, ketones, hydrocarbons, es-

. ters and alcohols; they may also be used, of

course, for packing against other fluids such as compressed air, oil, steam, water, and aqueous solutions.

Packing compositions such as have been ,described in the prior art are suitable for use at low pressures or in pumping or otherwise retaining liquids which do not have a solvent action on the packing, but owing to the rapid development of processes requiring the application of high pressures many of the older compositions are entirely inadequate. The most extreme requirements are experienced in packing pumps to be used on organic solvent mixtures at high pressures, as in the high pressure dehydrogenation of ethanol or the hydrogenation of organic acids, and esters, for example, in carrying out the process of U. S. Patent No. 1,708,460 and that described in my co-pending specification No. 445,224, filed April 17, 1930. No packing compositions of the prior art have been found capable of enduring for long the action of organic acids, and esters at pressures in excess of atm. By use of the new materials described in this specification it is now possible to pack the shafts of pumps in such a manner that no leakage takes place over a. long period of continuous operation.

The above description and specific examples are to be taken as illustrative only. Any departure therefrom which conforms to the spirit of the invention is intended to be included within the scope of the claims.

I claim:

1. A fluid-sealing material comprising a fibrous base impregnated with a hydrogenated castor oil, said castor oil having been hydrogenated to such a degree as to produce a. waxy materiai having a melting point of at least 70 C.

2. A fluid-sealing material comprising a fibrous base impregnated with a hydrogenated castor oil, and with a softener for said hydrogenated castor oil consisting of a fatty acid soap.

3. A fluid-sealing material comprising a fibrous base impregnated with a mixture comprising a hydrogenated castor oil, and a solid lubricant, said castor oil having been hydrogenated to such a degree as to produce a waxy material having a melting point of at least 70 C.

4. The method of making a fluid-sealing material which comprises passing a body of a fibrous base into a bath containing a molten hydrogenated castor oil, then removing the impregnated base from the bath, said castor oil having been hydrogenated to such a degree as to produce a waxy material having a melting point of at least 70' C.

5. The method of sealing fluids which comprises applying to fluid leakage outlets a packing composition comprising a fibrous base impregnated with a hydrogenated castor oil. said aoaasso castor oil having been hydrogenated to such a degree as to produce a waxy material having a melting point of at least 70 C.

6. In a method of carrying out a catalytic reaction under high pressure wherein at least one of the reactants is an organic solvent, the step which comprises preventing leakage by packing fluid leakage outlets with a composition comprising a fibrous base impregnated with a hydrogenated castor oil, said castor oil having been hydrogenated to such a degree as to produce a waxy material having a melting point of at least 7. The method of making a fluid-sealing material which comprises the steps of heating hydrogenated castor oil and a fatty acid soap to form a molten mixture and impregnating a fibrous base material with the molten mixture, said castor oil having been hydrogenated to such a degree as to produce a waxy material having a melting point of at least 70 C.

8. The method of making a fluid-sealing material which comprises the steps of heating hydrogenated castor oil and an inert solid lubricant to form a molten mixture and impregnating a fibrous base material with the molten mixture, said castor oil having been hydrogenated to such a degree as to produce a waxy material having a melting point of at least 70 C.

9. The method of making a fluid-sealing ma terial which comprises the steps of heating hydrogenatecl castor oil, dry sodium soap, and graphite about 10 minutes, removing, draining, and ala0 lowing to cool the impregnated asbestos.

WILBUR A. LAZIER. 

